1. Technical Field
The present invention relates to an optical module, an electronic apparatus, and a method of driving the optical module.
2. Related Art
The related art (for example, JP-A-2013-17507) discloses a spectrometry apparatus as an electronic apparatus including a spectroscopic element that can extract light of a predetermined wavelength from incident light and can change the extracted wavelength, and an imaging element that photodetects the light extracted by the spectroscopic element, and in which the spectrometry apparatus performs a spectroscopic measurement by detecting the amount of light photodetected by the imaging element.
JP-A-2013-17507 discloses a spectroscopic imaging apparatus (spectrometry apparatus) including an imaging element that alternates a light shielding period and a light exposure period; a spectroscopic element that can change an interplanar spacing of facing optical substrates; and an interplanar spacing control unit that controls the interplanar spacing.
In the apparatus disclosed in JP-A-2013-17507, the interplanar spacing control unit outputs a control signal, and controls the spectroscopic element to end an operation of changing the interplanar spacing at the end of a predetermined light shielding period of the imaging element, while taking account of the fact that the spectroscopic element starts and ends the changing operation at delayed timings with respect to an output timing of the control signal.
However, in the apparatus disclosed in JP-A-2013-17507, the predetermined light shielding period is set to be much longer than the changing operation regardless of the time required for the changing operation. For this reason, a measurement time increases by the time from the start of the light shielding period to the start of the changing operation.
The technology disclosed in JP-A-2013-17507 does not take account of a case in which a rolling shutter-type imaging element is provided that includes a plurality of pixel rows, drives each of the pixels rows at a different timing, and outputs a detection signal. That is, in the rolling shutter type imaging element, each of the pixel rows is driven at a different timing, and the amount of light exposure for two frames may be concurrently detected.
That is, initially, the pixel rows perform a photodetection process for a first frame, and immediately after that process, start a photodetection process for a second frame subsequent to the first frame. At this time, the pixel rows exist that continue to perform the photodetection process for the first frame.
Accordingly, when the spectroscopic element is driven without taking the drive timing for a photodetector element into consideration, as described above, the spectroscopic element may be driven at a time when the amount of light exposure for two frames is concurrently detected. At this time, both of the first and second frames becomes an invalid frame from which it is not possible to detect the amount of light exposure in a state where the set wavelength of the spectroscopic element is set to be the same for the entirety of the pixel rows, and it is not possible to acquire a high-precision spectroscopic image. The detection of the amount of light exposure for a third frame subsequent to the invalid second frame is started after the driving of the spectroscopic element is completed, and the third frame becomes a valid frame. As such, when the spectroscopic element is driven without taking the drive timing for the photodetector element into consideration, the invalid first and second frames are in succession, and a measurement time increases.